Compact firearms are desirable for outdoor activities, particularly those occurring in remote areas, including backpacking, boating, camping, backcountry flying, mountain biking, and hunting. A compact rifle is particularly attractive relative to a pistol because of the rifle's increased accuracy and range.
Since the compact firearm is often carried on the body, low weight is also desirable in addition to the ability to fit in a small space. Aluminum and plastic are attractive materials because of their light weight and low cost. However, a firearm made out of aluminum or plastic has the risk of apertures stretching over time from discharge impulses and denting caused by wear. In the case of an aluminum or plastic rifle, the mating engagement between the upper receiver and the lower receiver can become loose over time or as a result of subsequent firearm manufacturing activities after the receivers are initially made. Any looseness can lead to worsening accuracy over time and a perception of the firearm having poor quality on the part of the user.
Therefore, a need exists for a new and improved compact survival firearm that can be easily adjusted to compensate for loosening of the mating engagement between the upper receiver and the lower receiver. In this regard, the various embodiments of the present invention substantially fulfill at least some of these needs. In this respect, the compact survival firearm according to the present invention substantially departs from the conventional concepts and designs of the prior art, and in doing so provides an apparatus primarily developed for the purpose of enabling easy adjustment to compensate for loosening of the mating engagement between the upper receiver and the lower receiver.